The present invention relates to a provisional knee prosthesis and resection guide component together with a surgical procedure designed for use as a system in revision surgery of previously performed knee arthroplasties. It may also find utility in an initial knee replacement procedure.
Revision surgery is performed to correct failures of previously implanted knee prostheses. These failures occur for a number of reasons including malposition, loosening of the prosthesis, infection or dislocation. Such categories are not necessarily mutually exclusive since infection may cause a loosening of the prosthesis which, in turn, might cause dislocation.
When a prosthesis must be removed and a revision prosthesis inserted, it is often the case that additional bone must be removed in order to stabilize the new prosthesis. When this occurs, the interior portion of the femoral component of the prosthesis must be augmented to add additional thickness to compensate for the bone that has been removed. In addition, the revision cuts that remove the extra bone must be made correctly relative to the revision prosthesis for accurate positioning in relation to a tibial component and the soft tissues of the knee joint. Such cuts are made with the aid of guides positioned relative to the ends of the femur and tibia.
It is preferable to perform revision in a single surgical procedure. Also, it is desirable to be able to test the fit and operation of the prosthesis relative to the rest of the knee, particularly the patella and the soft tissues, prior to or at the same time as the revision cuts are made in the end of the femur. Indeed, with regard to patellar tracking, it is preferable to ensure a proper fit before the final anterior cuts are made to the distal femur.
The apparatus and method of this invention are intended to be used in conjunction with the revision prosthesis system of applicant's co-pending application which is based around a constant geometry of the anterior flange, the distal prosthesis and the intramedullary stem of the component and uses the intramedullary canal of the femur as a reference point. Accordingly, the present invention is similarly based around the intramedullary canal of the femur as a reference point for all of the bone cuts.